[ovs-discuss] Matchable port's external-ids

Liran Schour LIRANS at il.ibm.com
Sun Sep 2 13:26:23 UTC 2012

Ben Pfaff <blp at nicira.com> wrote on 29/08/2012 17:15:37:

> On Wed, Aug 29, 2012 at 03:07:26PM +0300, Liran Schour wrote:
> > Is it possible to assign some external IDs to a port and then force the
> > switch to send this IDs as a matchable field to the controller via OXM
> > each PACKET_IN message?
> > In other words I am looking for a way to assign IDs per port and to be
> > to send these IDs to the controller as matchable fields.
> You could match on the port number in the flow table, then assign a
> value to, say, the NXM registers or the OXM metadata field.  When the
> NXM packet-in format is in use (or OpenFlow 1.2+, once that is
> supported), then those fields will be passed to the controller.

When I add such a flow to the flow table, the switch stops sending
PACKET_IN messages to the controller. When I add the actions:...,controller
to the flow then the switch sends the requested PACKET_IN message with the
proper NXM registers value but it will continue to send PACKET_IN message
on each new packet according to this flow.
I want to create this flow with a low priority, means only if we do not
have any other match act according to this flow. I tried to use table
numbering but I see that if there is no match in table 0 the switch sends a
PACKET_IN to the controller and not continue to search on other flow
How can I achieve such behavior?

- Liran

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